Purinergic system ecto-enzymes participate in the thromboregulation of patients with indeterminate form of Chagas disease

Abstract

Chagas disease (CD) is a chronic and endemic illness caused by the parasite Trypanosoma cruzi. Microvascular disturbances play an important role in the progress of the disease. The purinergic signaling system participates in regulatory functions, such as immunomodulation, neuroprotection, and thromboregulation. This study aimed to investigate the activities of purinergic system ecto-enzymes present on the platelet surface and the platelet aggregation profile from patients with indeterminate form of Chagas disease (IFCD). Thirty patients diagnosed with IFCD and 30 healthy subjects were selected. Ecto-nucleoside triphosphate diphosphohydrolase (E-NTPDase), ecto-nucleotide pyrophosphatase/phosphodiesterase (E-NPP), ecto-5'-nucleotidase (E-5'-NT) and ecto-adenosine deaminase (E-ADA) activities were measured in platelets isolated from these individuals as well as the platelet aggregation. Results demonstrated an increase of 21 % in the E-NPP activity and 30 % in the E-5'-NT activity in IFCD group (P < 0.05); however, a decrease of 34 % in the E-ADA activity was determined in the same group (P < 0.001). A significant decrease of 12.7 % and 12.8 % in the platelet aggregation of IFCD group in two different concentrations of ADP (5 and 10 μM) was observed, respectively (P < 0.05). Increased E-NPP and E-5-NT activities as well as decreased E-ADA activity in platelets of patients with IFCD contributed to decrease platelet aggregation, suggesting that the purinergic system is involved in the thromboregulation process in these patients, since adenosine (the final product of ATP hydrolysis) has cardioprotective and vasodilator effects that prevent the clinical progress of the disease.

Fig. 1

E-NTPDase (ATP and ADP hydrolysis, (a and b), respectively) and E-5′-NT (AMP hydrolysis, (c)) in platelets of patients with indeterminate form of Chagas disease (IFCD). Bars represent means±SEM. The double asterisk symbol represents statistical difference from the control group (Student's t test, P < 0.01, n = 30)

Fig. 2

E-NPP activity in platelets of patients with indeterminate form of Chagas disease (IFCD). Bars represent means±SEM. The asterisk symbol represents statistical difference from the control group (Student's t test, P < 0.05, n = 30)

Fig. 3

E-ADA activity in platelets of patients with indeterminate form of Chagas disease (IFCD). Bars represent means±SEM. The three-asterisk symbol represents statistical difference from the control group (Student's t test, P < 0.001, n = 30)

Fig. 4

Platelet aggregation profile in patients with indeterminate form of Chagas disease (IFCD) and healthy subjects (control). Platelet aggregation was evaluated by using ADP as agonist at concentrations of 5 and 10 μM. The results are expressed as percentage of aggregation. The asterisk symbol represents statistical difference from the control group (Student t test, P < 0.05, n = 15)